Over the past century the demand for energy has grown exponentially. In particular, devices that use electrical energy have proliferated. Energy for such devices has historically been produced by the combustion of hydrocarbons to generate electricity that is then distributed over regional and local power grids. However, the combustion of hydrocarbons produces pollution.
Additionally, many electronic devices are now being made portable and wireless. Such devices require a compact and portable power supply. Batteries are typically used to power such portable electronic devices. However, batteries must either be disposed of when exhausted or recharged. If the battery used is rechargeable, the battery is typically connected to a recharger. The recharger is then plugged into a stationary outlet and takes power from the local power grid to recharge the battery.
With the increased interest in cleaner and more portable energy sources, fuel cells have become more popular and more sophisticated. Research and development on fuel cells has continued to the point where many speculate that fuel cells will soon compete with batteries in supplying electricity for a variety of portable devices both large and small.
Fuel cells utilize an electrochemical reaction between hydrogen and oxygen to produce electricity and heat. Fuel cells can be made similar to batteries, but they can be “recharged” while still providing power. Fuel cells provide a DC (direct current) voltage that may be used to power motors, lights, or any number of electrical appliances. Proton exchange membrane (PEM) fuel cells are particularly practical because of their low operating temperature and adaptability in portable applications.
Unfortunately, hydrogen, a principal reactant used in fuel cells, is historically difficult to store and distribute as compared to conventional fuels. Previous attempts to produce hydrogen from various reactants have faced challenges such as precipitates in the reaction, the volatility of the reaction, low yield, and lack of efficiency. Once produced, hydrogen is typically compressed and stored in tanks. However, such hydrogen tanks have low gravimetric storage efficiency and are under higher pressures.
Consequently, hydrogen is preferably produced at a point near a fuel cell, rather than a centralized production facility. Thus, to be effective, hydrogen generation for fuel cells should preferably be simple, compact, portable, and relatively inexpensive. Furthermore, a hydrogen generator for use with a fuel cell is preferably integrated with the operation of the fuel cell to allow the fuel cell to control the hydrogen generator. This is useful because the demand for hydrogen varies depending on the power output the fuel cell needs to produce.